CVE-2026-16158
8.7 · HIGHOverview
CVE-2026-16158 is a high-severity vulnerability affecting fastify fastify\/reply-from. It was published on July 18, 2026 and has a CVSS 3.1 base score of 8.7 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.7, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Impact: @fastify/reply-from versions from 8.3.1 up to but not including 12.6.4 build the internal URL cache key by concatenating the destination and source path without a delimiter. Different destination and source pairs can therefore produce the same key while resolving to different upstream URLs. When getUpstream selects an upstream from request data, a URL cached for one upstream can be reused for a request intended for another upstream, causing cross-upstream data access and modification. The default configuration is affected. Setting disableCache to true prevents the behavior. Patches: upgrade to @fastify/reply-from 12.6.4. Workarounds: pass disableCache: true when registering the plugin.
Remediation
Check the references section for vendor advisories and patches from fastify. Update fastify\/reply-from to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| fastify | fastify\/reply-from | >= 8.3.1, < 12.6.4 | Affected |
Frequently Asked Questions
What is CVE-2026-16158?
CVE-2026-16158 is a high-severity vulnerability affecting fastify fastify\/reply-from. It was published on July 18, 2026 and has a CVSS 3.1 base score of 8.7 (HIGH).
How severe is CVE-2026-16158?
This vulnerability has a CVSS 3.1 base score of 8.7, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-16158?
Check the references section for vendor advisories and patches from fastify. Update fastify\/reply-from to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-16158?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-16158 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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